Question

I’m doing audio sampling with waveInProc callback. The problem is that when I’m trying to stop sampling and close the audio device I get no msg in the callback – tried waveInStop, waveInClose, waveInReset.

Pls advice.
10xs,
Nahum

HWAVEIN  hWaveIn
waveInOpen(&hWaveIn,WAVE_MAPPER,&waveform,(DWORD)waveInProc,0, CALLBACK_FUNCTION);
waveInStart(hWaveIn);

waveInStop(hWaveIn); //OR
waveInClose(hWaveIn); //OR
waveInReset(hWaveIn); //OR

UPDATE: Here is the code:

Starting:

waveInOpen(&hWaveIn,WAVE_MAPPER,&waveform,(DWORD)waveInProc,0, CALLBACK_FUNCTION);
waveInPrepareHeader(hWaveIn,pWaveHdr1,sizeof(WAVEHDR));
waveInAddBuffer(hWaveIn,pWaveHdr1,sizeof(WAVEHDR));
waveInStart(hWaveIn);

---

 void CALLBACK waveInProc(  HWAVEIN hwi, UINT uMsg, DWORD dwInstance, 
                            DWORD dwParam1,   DWORD       dwParam2    )
  {

     if (uMsg == WIM_OPEN)
     {
     return;
     }
     if (uMsg == WIM_DATA)
     {
     //process data
     waveInAddBuffer(hWaveIn,(PWAVEHDR)dwParam1,sizeof(WAVEHDR));
     return;
     }
     if (uMsg == WIM_CLOSE) //NOT GETTING THIS MSG

     {
      printf("*****************got WIM_CLOSE\n");
     }
 }

---

So how to stop sampling and close the audio device?

---

Here is the code:
Starting:

waveInOpen(&hWaveIn,WAVE_MAPPER,&waveform,(DWORD)waveInProc,0, CALLBACK_FUNCTION);
waveInPrepareHeader(hWaveIn,pWaveHdr1,sizeof(WAVEHDR));
waveInAddBuffer(hWaveIn,pWaveHdr1,sizeof(WAVEHDR));
waveInStart(hWaveIn);

---

 void CALLBACK waveInProc(  HWAVEIN hwi, UINT uMsg, DWORD dwInstance, 
                            DWORD dwParam1,   DWORD       dwParam2    )
  {

     if (uMsg == WIM_OPEN)
     {
     return;
     }
     if (uMsg == WIM_DATA)
     {
     //process data
     waveInAddBuffer(hWaveIn,(PWAVEHDR)dwParam1,sizeof(WAVEHDR));
     return;
     }
     if (uMsg == WIM_CLOSE) //NOT GETTING THIS MSG

     {
      printf("*****************got WIM_CLOSE\n");
     }
 }

---

So how to stop sampling and close the audio device?

10xs,
Nahum

Answer 1

Are you checking your waveInOpen result?

Because it works as expected:

hWaveIn 0x005B7768, nMessage 0x03BE, nInstance 0, nParameter1 0, nParameter2 0
nWaveInOpenResult 0, hWaveIn 0x005B7768
hWaveIn 0x005B7768, nMessage 0x03BF (WIM_CLOSE), nInstance 0, nParameter1 0, nParameter2 0

Code:

#include "stdafx.h"
#include <mmsystem.h>

#pragma comment(lib, "winmm.lib")

VOID CALLBACK waveInProc(HWAVEIN hWaveIn, UINT nMessage, DWORD_PTR nInstance, DWORD_PTR nParameter1, DWORD_PTR nParameter2)
{
    _tprintf(_T("hWaveIn 0x%p, nMessage 0x%04X, nInstance %d, nParameter1 %d, nParameter2 %d\n"), hWaveIn, nMessage, nInstance, nParameter1, nParameter2);
}

int _tmain(int argc, _TCHAR* argv[])
{
    WAVEFORMATEX Format = { WAVE_FORMAT_PCM, 1, 8000, 16000, 2, 16, 0 };
    HWAVEIN hWaveIn = NULL;
    const MMRESULT nWaveInOpenResult = waveInOpen(&hWaveIn, WAVE_MAPPER, &Format, (DWORD_PTR) &waveInProc, 0, CALLBACK_FUNCTION);
    _tprintf(_T("nWaveInOpenResult %d, hWaveIn 0x%p\n"), nWaveInOpenResult, hWaveIn);
    waveInStart(hWaveIn);
    waveInStop(hWaveIn);
    waveInClose(hWaveIn);
    return 0;
}

While processing data in real code make sure to take this into consideration: within the callback function:

Applications should not call any system-defined functions from inside
a callback function, except for EnterCriticalSection,
LeaveCriticalSection, midiOutLongMsg, midiOutShortMsg,
OutputDebugString, PostMessage, PostThreadMessage, SetEvent,
timeGetSystemTime, timeGetTime, timeKillEvent, and timeSetEvent.
Calling other wave functions will cause deadlock.

To re-add buffer, you need to indicate such as need by signalling to another thread, using PostMessage or SetEvent, so that your code outside of the callback could receive this indication and re-add the empty buffer from there.